The present invention relates to an optical device and a production method therefor. In particular, it relates for example to an optical low-pass filter and a production method therefor, which prevents damage during transportation, while increasing productivity and yield.
Optical low-pass filters are built into various electronic equipment incorporating optical systems, being located in front of the imager in optical devices such as cameras, and are used to prevent color blur by utilizing their birefringence. In recent years, electronic equipment with built in optical systems are becoming increasingly common, thus increasing their demand. It is therefore desired to prevent damage so that optical characteristics can be maintained with certainty, and also to prevent negative effects on other optical devices.
FIG. 4 to FIG. 6 illustrate a conventional production example of an optical low-pass filter.
As shown in FIG. 5, an optical low-pass filter 1 comprises a laminate where a plurality of, for example three, optical plates 1a, 1b, 1c, made up from optical plates of chip-form glass or crystal made into a veneer, are bonded together and laminated by an adhesive. For this adhesive, for example an ultraviolet curing adhesive may be used.
Usually in a conventional production method for an optical low pass filter, firstly as shown in FIG. 4, a laminated wafer is obtained by bonding together and laminating a plurality of optical wafers (composed of glass or crystal) with adhesive, and then dividing this into individual laminates by cutting with a dicing saw.
Next, the laminates (optical low-pass filters 1) are manually lined up one by one in a washing device and washed and dried, and then inspected visually. Lastly, as shown in FIG. 5, one face (bottom face) of the optical low-pass filter 1 is affixed to the surface of a double sided adhesive tape 3 which is also affixed to a mount 2 inside a packing box, and the optical low-pass filter 1 is then stored and shipped in a fixed, inverted position. As a result, damage to the optical low-pass filter 1 due to vibrations and shocks during transportation, and coming into contact with other equipment is prevented.
However, in the conventional production method for an optical low-pass filter as described above, a problem is that the optical low-pass filters (optical plates) 1 consisting of laminates, must be manually aligned in the washing device one-by-one by an operator. A further problem is that, as shown in FIG. 5, to individually invert the optical low-pass filters (optical plate) 1 onto the mount 2 is extremely inefficient so that productivity and yield is low.
Taking into account these problems, mass automation of the washing and packing of optical low-pass filters 1 has been devised. However, since the optical low-pass filter 1 is composed of brittle material (for example, glass and crystal), there is a fear of causing damage (such as chipping) to the periphery thereof, particularly in the production process when it comes into contact with automated equipment. Moreover, when the optical low-pass filters 1 are packed, then as shown in FIG. 6, a packing box 4 with small gutters, has these small gutters in bottomed crevices 5 formed in the packing box 4, and each optical low-pass filter 1 is attached for example by the principal plane of the optical low-pass filter 1, into the crevice 5 by automatic transfer from the previous process. However, even in this case, the optical low-pass filter 1 becomes damaged by colliding with the inner walls of the crevice 5 due to vibrations during transportation. Such damage causes minute debris produced by the damage to adhere to the midsection of the principal plane of the optical low-pass filter, causing deterioration of optical characteristics.
In particular, the optical low-pass filter 1 of the construction described above, is normally formed by dividing a laminated optical wafer (laminated wafer) by a dicing saw. In this case particularly the cutting plane (cleavage plane) of the laminated wafer can have minute and sharp protrusions (burrs), and be jagged. Consequently, these protrusions tend to form minute debris by becoming detached from the cutting plane due to shock and vibration. Moreover, such minute debris can cause negative effects on other electronic devices built into electronic equipment.
Here, the optical device is described as a laminated optical low-pass filter, but the same problems generally arise in optical devices including a wave plates comprising veneers.